Process of preparing nonwoven fabric and product



atentecl Apr. 20, 1954 UNITED STATES PATENT orrlcs PROCESS OF PREPARING NONWOVEN FABRIC AND PRODUCT John Augustus Piccard, Swarthmore, Pa... amignor to E. I. du Pout de Nemours & Company, Wilmington, DeL, a corporation of Delaware No Drawing. Application June 18, 1951, Serial No. 232,245

17 Claims. (Cl. 154-101! and various natural fibers, such as cotton, wool and silk to produce both woven and non-woven fabrics for a great many uses.

When woven fabrics are used for certain applications such as a base or substrate for flexible coatings in the. manufacture of upholstery, pocketbooks, and artificial leather in general the fabric weave pattern shows through the surface coatings and is generally undesirable. Many attempts have been made to overcome this undesirable characteristic of coated woven fabrics. The use of felts or non-woven fabrics made from various fibers and fiber combinations has been tried many times as a substrate for flexible coatings in the manufacture of various artificial leather products. The non-woven fabrics produced heretofore for this purpose have lacked sufllcient tensile and tear strength or are too still and boardy to be of any appreciable value. Also .the felts or non-woven fabrics available heretofore for this purpose have resulted in a very uneven coated surface such as'an exaggerated orange peel effect.

An object of this invention is the production of non-woven fabrics which have greatly improved physical properties. A further object is the production of a non-woven fabric having improved tensile and tear strength. These and other important objects will be readily apparent as the description of the invention proceeds.

These and other important objects are accomplished according to the present invention by the provision'of a non-woven fabric comprising non-fusible or relatively non-fusible fibers, which form the fabric structure, bonded together by means of certain fusible elastic polyesters defined more fully hereinafter. I The relatively nonfusible fibers may consist of cotton, nylon, viscose rayon, cellulose acetate, polyethylene terephthalate, polymers of acrylonitrile, copolymers containing at least 85% acrylonitrile, wool, glass and mixtures thereof.

The 'term non-fusible or "relatively nonfusible as used throughout the specification and appended claims refers to a structural fiber havinga fusion temperature higher than the fusible polyester, referred to hereinafter as the binder.

.Thedifferentiai in the temperature at which the structural fiber and the binder develop adhesive 2 properties should preferably be about 50 F. for commercial operations. Under certain controlled conditions this temperature differential may be less than about 50 F.

I The copolyesters employed for the fusible or binding material are similar to those prepared by copolymerizing under melt polymerization conditions and within certain composition limits hereinafter set forth, at least one acyclic dicarboxylic acid of the formula HOOC -CHsXCHr-COOH ethylene bis p-oxybenzoic acid, tetramethylene bis p-oxybenzoic acid, and 2,6-naphthalic acid and with a polymethylene glycol of the formula HO (CH2) aOH The relative amounts of aliphatic and aromatic acids to be used are critical inpreparing copolyesters for the purpose of this invention, since if too much of either one is used the copolyester tends to be too crystalline to produce highly elastic polymers. Therefore,- to make the elastic copolyester for the purpose of this invention, it is necessary that the aromatic acid comprise at least 30% and not more than by weight of the total acid component of final polymer.

A preferred range is 55-65% of the aromatic acid.

It is a simple matter. to obtain any desired ratio of acid components in any one copolyester. The acids will be present in the final polymer in the. same ratio as they were present in the initial reactants provided an excess of glycol is used. It should be understood, of course, that many combinations of these aliphatic and aromatic acids may be Thus, two or more aliphatic and/or two or more aromatic acidsmay be used to form the copolyester. It is also to be understood that 3 the ester-forming derivatives of these acids can be used in place of, and are the full equivalents of the acids described above as is generally the case in the manufacture of linear polyesters.

4 subjected to heat and pressure by passing between heated calender rolls under pressure or pressed between heated plates. The heat required must be suflicient to render the polyester In addition to the copolyesters described above 5 fiber adhesive and have no appreciable effect on and disclosed in copending application Serial No. the relatively non-fusible or structural fibers. 150,811, now U. S. Patent 2,623,033, the melt mix- In actual practice a plurality of single webs from tures of polyesters and copolyesters described in the card are superposed in parallel arrangement copending Serial No. 150,812 filed March 20, 1950, or alternately crosslapped in va manner well by M. D. Snyder, now U. S. Patent 2,623,031, known in the art of felt making. may also be used as the binding medium for the For the purpose of direct comparison the folnon-fusible structural fibers. The melt-blends lowing specific examples were carried out using are prepared by first preparing the copolyester substantially the same length staples at constant described above and thereafter melt-blending the denier. copolyester thus formed with an aromatic polyl5 EXAMPLE; I ester prepared by melt polymerizing a symmetrical aromatic dibasic acid from the group con- Monofilaments were prepared by melt spinning sisting of terephthalic acid, blbenzoic acid, tetraa copolyester consisting of 40 parts ethylene methylene bis p-oxybenzoic acid, and 2,6-naphglycol sebacate per 60 parts of ethylene glycol thalic acid, and a polymethylene glycol of the terephthalate. The copolyester had a fusion formula HO(CH:) "OH, n being a whole number temperature of approximately 320 F. The cofrom 2 to 6 inclusive. Preferably, the same aropolyester fiber was cut into staple of approximatic dibasic acid used in the copolyester is mately 1 inch length. After this staple was used in the polyester. As in the case of the coopened it was thoroughly mixed with an equal polyester, the aromatic acid component of the 5 quantity of long staple cotton fibers of approximelt-blend of the polyester and copolyester mately 11 inch length. This mixture was then should be at least and not more than 70% carded in the form of a web weighing approxion a weight basis. mately .66 ounce per square yard in a fashion A preferred embodiment of this invention is usually employed in the manufacture of non- 'carried out by preparing non-woven fabrics by 30 woven fabrics. Twelve separate webs were intermingling non-fusible structural fibers such superposed in such a manner that alternate webs as'cotton, viscose rayon, cellulose acetate, nylon, werecrosslapped at substantially right angles. polyethylene glycol terephthalate, polymers of The entire assembly was pressed for one minute acrylonitrile, copolymers containing at least 85% between the platens of a hydraulic press at a acrylonitrile, wool, and glass, with the polyester temperature of 365 F. and at a pressure of 400 fibers described above. The blending of the fibers p. s. 1. The felt produced was 15 to 20 mils thick is carried out mechanically or manually in acand weighed approximately 8.0 ounces/square cordance with well established procedures in the yard. It was suitable for the applications mentextile art. An alternate method is to introduce tioned hereinafter,- the copolyester binder in the form of a solution 40 The copolyester in this example may be preinto a preform m of Structural fibers whi h pared in accordance with the disclosure in copermeates the fibers and binds them together pending application Serial No. 150,811 filedMarch upon evaporation of the solvent. Another al- 20, 1950, n w U, 3, Patent 2,623,033. ternate method is to distribute the polyester LE binder throughout the assembly of preformed 5 EXAM? n bats of structural fiber in the f rm 01 fin ly Another felt was made in the same manner as divided particles and then activating the adhesive d i d n Example 1 except; t ati of prop ti s o e Polyester by bjecti t 11 polyester fibers to cotton fibers was 1 to 2. sembly to heat and pressure and/or by treatment with a solvent for the polyester. Still another EXAMPLE m alternate method is to introdu h ind Another felt was produced in the same manthrou h ut th Structural fiber mat in the form ner as described in Example I except the ratio of of an aq e u suspension which y b u d or copolyester fibers to cotton fibers was 1 to 3. dissolved after drying by subjecting the impregnated mat to heat and pressure and/or a solvent XAMPLE IV for the binder. Another felt was produced in the same man- In the Preferred Practice Dlumlity 0f the ner as described in Example I except the ratio loosely bound we from the c or other met or copolyester fibers to cotton fibers was 1 to 4.

, forming equip a sup p in parallel The following table is a summary of the physiarrangement or they may be crosslapped at right 00 cal properties of the felts described in Examples or acute angles. The superposed webs are then I to IV.

Table I 1 II shit; Temlm fi$ s (lbs) Elg g iih n Ex p gag 8mm, tti lireak ing Hand Fiber WIF! WplusF w r WplusF su gfw 365 5063 13 a as E? 81. 2 4to1 365 8/18 as sI0' 2I7 s11 '4 1'3 i o gselyboundnndlow tensile strength.

1 The tensile strength, tongue tear and elongation tests were carried out in accordance with the procedures desaibed in ASTM, D3949 The l tter; W" and "F" refer to the conventional warp and filler direction of woven fabrics. In thisinstaneeand mthaWW'rdentothe tion of the non-woven fabric and the "1" refers to the moss-machine di- EXAMPLEV A non-woven fabric was prepared in the same manner as described in ExampleI in which the structural fiber (non-binding) was 3.0 denier nylon monofiiament staple approximately 1% inches long. Three parts by weight of this staple were mixed with one part of the copolyester staple fiber referred to in Example I. The mixed staples were carded and formed into a web. Twelve separate webs were crosslapped, and compacted by passing between calender rolls heated to 265 F. at a rate of 6 ft. per minute, with the calender rolls opened to 4 mils. The resulting felt was approximately 8.0 oz./sq. yd. and 16 mils thick. It was smooth and exhibited unusually high tensile and tear strength as shown in Table II.

The nylon polymer in the above example is a synthetic linear polyamide resulting from the reaction of hexamethylene diamine and adipic acid and may be produced in accordance with the teachings in U. S. Patents 2,071,250 and 2,071,251.

EXAMPLE VI A non-woven fabric was produced in the same manner as described in Exam le V except the relatively non-fusible structural fiber was a polyester of ethylene glycol and terephthalic acid and the binding fiber was the copolyester referred to in Example I and nine separate webs were employed in crosslapped relation. Three parts of the polyester fiber were blended with one part of copolyester fiber. The compacting was carried out by calendering in the same manner as described in Example V. The non-woven fabric weighed approximately 8.0 ounces/square yard and was soft and flexible.

The polyethylene terephthalate may be produced in'accordance with the disclosure in U. 5. Patent 2,465,319.

EXAMPLEVII A non-woven fabric was prepared in the same manner as described in Example V except viscose rayon 3.0 denier, 1 inch staple monofilaments were used as the structural fiber.

EXAMPLE VIII Example V was repeated using 1 /2 inch long staple cotton fiber in place of the nylon asthe structural fiber.

The following Table H summarizes the physical properties of the non-woven fabrics referred to 1 ounce per square yard. Eight separatewebs were superposed and then placed between two sheets of 80 mesh wire screen. The assembly was subjected to moderate pressure by hand to compact the superposed plies. The entire assembly was then dipped into a 5 solution of a copolymer of parts of ethylene glycol terephthalate and 40 parts of ethylene glycol sebacate dissolved in chloroform. The assembly was then removed from the solution and the excess solution was allowed to drain off. To facilitate saturation of the superposed webs the assembly was subjected to the action of a hand roller on each side. The assembly was then dried at 250 F. until the chloroform was evaporated. The .wire screens were then removed from the web and the dried web further condensed by passing between pressure rolls heated to about 265 F. A soft, high strength unitary non-woven felt was obtained.

EXAMPLE X A non-woven felt-like fabric is produced by forming a web of long staple (11 inch cotton fibers) and superposing eight separate webs to form a bat. Finely divided copolyester of 60 parts ethylene glycol terephthalic acid and 40 parts ethylene glycol sebacate is distributed throughout the assembly; The entire assembly consists of about cotton fibers and 25% copolyester on a weight basis. The finely divided copolyester is distributed on the surface and at least to some extent throughout each individual web. The entire assembly is next pressed between heated platens at a temperature of about 350 F. for a period of 1 minute. The resultant product is a soft high strength non-woven fabric suitable for use as substrate for flexible coatings and other uses where high strength non-woven fabrics are required. 1

EXAMPLE XI The blended fibers were carded in the form of a web weighing about ounce per square yard. Iwelve separate webs were superposed, the first four webs in parallel arrangement, the

1;; Examples V to V111. second four in parallel arrangement and at right Table II Properties of Non-Woven Fabric Tensile (lbs. per Percent Example Structural Fiber Binding Fiber amp) Tongue Tear (lbs.) Elongation to Breaking Hand Point &" W/F W plus F W/F W plus E Strip), [F

v Nylon Oopolyester, Same 67/88 21/31 58 76/80 Soft and Flexible. as in Example I. L V1 Polyester oi Ethylene do 2)]62 8. 5/l0.5 19 63/63 Do.

Glycol and Terephthallc Acid. VII "iscoso Rayon .110 18/34 52 1/5 6 11/16 Do. VIII Cnflnn 14/17 31 3. 7/4 7. 7 22/22 Do.

EXAMPLEIX A non-woven felt-like fabric was produced b carding the nylon fiber referred to in Example V angles to the first four and the third four were in parallel arrangement. and at right angles to into the form of a web weighing approximately 76 compacted by passing between even speed high 7 pressure rolls heated to about 265 F. and set about4milsapart.

The assembly was compacted to approximately mils thick and weighed approximately 8.0

ounces per square yard. The felt-like material had the following physical properties: w/F Tongue tear lbs 31/31 Tensile-1" striplbs.. 74/50 Per cent elongation to breaking point"--- 75/57 EXAMPLE XII A non-woven felt-like fabric was made in the same manner as described in Example 21 except the following blend of fibers was employed:

Parts by weight Polyacrylonitrile (1 staple, 3.0 denier) 3 copolyester of 60 ethylene glycol terephthalate and 40 ethylene glycol sebacate (1 V staple, 3.0 denier) Twelve carded webs were superposed with alternate sets of four webs crosslapped and the assembly compacted by passing between heated (265 F.) pressure rolls set 4 mils apart. The resulting product weighing 8.1 ounces per square yard was suitable as a substrate for flexible coatings. It had the following physical properties: w/F

Tensile strength-4" strip -lbs 33/45 Tongue tear lbs 8/13 Per cent elongation to the breaking point... 45/50 EXAMPLEXIII A non-woven felt-like fabric was produced by carding the following blend of fibers on a hand card: G

The polyethylene glycol terephthalate and the copolymer were blended in a ratio so that the aromatic acid component was 70% by weight of the total acid component of the blend. Two separate bats about 10" square were produced from a blend of the above fibers. The two separate bats were superposed and trimmed to about 8" square. The superposed bats were pressed at about 320 F. and aproximately 500 p. s. i. The assembly was firmly bonded and was a flexible felt-like fabric.

The melt-blended fibers, in the above formula, develop adhesiveness'at about 350-390 F. In the above example they serve as structural fibers. When higher melting structural fibers are employed, such as, e. g. nylon, this melt-blend may be used as binding fibers.

For the purpose of this invention it is important that the structural fibers not develop any adhesiveness at the temperature at which the binder is rendered adhesive. The copolyesters described above have a fusion temperature of 300-400 F. They do not have a true melting point in the ordinary sense of the word. The temperature at which adhesiveness develops depends more or less on the degree of crystallinity of the polymer and is lower than the fusion temperature. The preferred polyester binder containing 60 parts of ethylene glycol terephtba- 8 I late and 40 parts ethylene glycol sebacate has a fusion temperature, approximateLv 320 F. al-' though adhesiveness develops at a lower temper- I ature. The invention is not to be limited to the particular temperature range mentioned above for the fusion temperature of the copolyester binder. The important thing is that the binder develop adhesiveness at about 50 F. lower than the structural fiber. The fusion temperature is not to be confused with the temperature at which adhesiveness develops. When a thermoplastic fiber is used as the structural fiber it must not loose its identity as a fiber during the processing. Nylon is particularly preferred as the structural fiber in view of its relatively high melting point (approximately 482 F.) and high tensile and tear strength. The wide diiference in temperature at which adhesiveness is developed in the nylon polymer and the copolyesters provides a safe operating range for the practice of this invention.

It is also possible to improve the adhesiveness of the binding fiber by treating the matted felt after the compacting operation with a volatile liquid which renders the binding fiber cementitious.

The copolyesters and melt-blend of polyesters and copolyesters described above are particularly useful for the purpose of this invention in view of their elastic recovery when elongated. Conventional non-woven, fabrics and papers tear relatively easily when a strip is cut on one edge and the cut edges are subjected to opposing forces since the fibers are broken one at a time as the entire stress is applied to a relatively few fibers. When the non-woven fabrics employing the elastic copolyesters and melt-blended polyesters and copolyesters as the binding medium are cut on one edge and the cut edges are sub- Jected to opposing forces the elastic fibers stretch and the stress is distributed over a greater number of fibers than in the case of conventional non-woven fabrics.

A commercial grade of felt weighing about 8 ounces/square yard comprising a blend of viscose rayon, cotton, and a binding fiber consisting of copolymer of parts of vinyl chloride and 15 parts of vinyl acetate was subjected to the same tests as shown in Tables I and II with the following results:

Felt, 8 1 1 y Tensile Strength 1" strip (WXF) 9X13 lbs. Y Tear Strength (Tongue) 32x52 lbs.

A comparison of the above data with Tables I and II illustrates the advantages of the products of this invention over prior art material of equal weight.

The copolyesters and melt-blended copolyesters and polyesters described in copending application Serial No. 150,811 and Serial No. 150,812 both filed March 20, 1950, U. S. Patents 2,623,033 and 2,623,031, respectively, when used in this invention in'the form of fibers may be cold drawn, that is, permanently elongated by tensile stress in order to orient them since the oriented filaments have greater strength and elasticity. The unoriented or but slightly oriented fiilaments obtained by spinning under little or no stress are, however, also useful in the practice of this invention.

The various copolyesters described above used 9 to form the non-woven fabric may be plasticized or unplasticized. If a softer binding fiber or one which develops adhesiveness at a lower temperature is desired it may be plasticized with an aryl sulfonamide, such as toluene sudfonamide or amylbenzene sulfonamide.

The proportion of thermoadhesive binder to the non-thermoadhesive fiber used in the examples illustrate the preferred proportions. Where very soft fluffy felts are desired the binder may represent as little as of the total and when very stiff and boardy felts are desired the binder may represent as high as 65 of the total.

The time, temperature and pressure used in the specific examples may vary depending upon the nature of the thermoadhesive or binding fiber, particularly its softening point, and on the nature of the structural or non-thermoadhesive fibers present. For example, if a high melting filament is used as the binding fiber a relatively higher temperature and pressure will be required than if a low melting filament is used. Likewise, if a soft fabric is desired a lower pressure and/or temperature will be used than if a hard fabric is desired. Also, at higher pressures lower' temperatures may be employed.

The fabrics produced in accordance with this invention can be dyed by the usual methods either by application of the dye to the formed felt or to the fibers before carding.

The physical properties of the fabric such as, e. g., its feel and tackiness may be altered, if desired, by subjecting the fabric to flufiing and steaming treatments.

The denier of the filaments which may be used in carrying out this invention may vary depending on the type and appearance of the nonwoven fabric desired. While the three denier filament is preferred, filaments having a denier of one or less may be used. Fibers having a denier of to '70 produce useful non-woven fabrics and where extremely coarse felt is desired, even coarser filaments having a denier of 100 to 150 may be used. The thermoadhesive binding filament and the non-thermoadhesive structural fiber may be straight or crimped.

The non-woven fabrics of this invention, depending upon the particular fibers used and upon the conditions of treatment, possess a wide range pended in a plasticizer, such compositions are referred to as plastisols." Where the suspending medium is an organic volatile liquid such compositions are referred to as onganosols. Also the flexible coatings may be applied by the well known calendaring methods. The flexible coatings may be applied to either or both sides of the non-woven fabric. The absence of a weave pattern in the non-woven fabric makes it particularly useful as a substrate for flexible coatings where a fabric weave pattern is objectionable.

The coated products referred to above are disclosed and claimed in a copending application 5. N. 232,247, filed June 18, 1951, by E. A. Rodman,

It is apparent that many widely different embodiments of this invention may be made without departing from the spirit and scope thereof and, therefore, it is not intended to be limited except as indicated in the appended claims.

I claim:

1. A non-woven fabric comprising compacted structural staple fibers selected from the group consisting of cotton, nylon, viscose rayon, cellulose acetate, polyethylene terephthalate, polymers of acrylonitrile, wool and glass, bound together by a binding material comprising a linear copolyester of (a) at least one polymethylene glycol ester of an acyclic dicarboxylic acid of the formula wherein X is a linear chain composed of 4 to 9 atoms, in the chain of which not more than 3 may be oxygen atoms and the remaining are hydrocarbon carbon atoms, any two such oxygen atoms being separated by at least two such carbon atoms, the hydrocarbon carbon atoms being saturated and containing a total of not more than three hydrocarbon carbon atoms as side chain su bstituents, with (b) at least one polymethylene glycol ester of a symmetrical aromatic dibasic acid from the group consisting of terephthalic acid, bibenzoic acid, ethylene bis-p-oxy-benzoic acid, tetramethylene bis-p-oxy-benzoic acid and 2,6-naphthalic acid, the aromatic acid comprising from 30% to 70% by weight of the acid components of the copolyester and the polymethylene glycol component of (a) and (b) having from 2 m to 6 carbon atoms, the binding material being present in amount between 10% and 65%, based 1 on the combined weight of the binding material and the structural fibers.

2. The product of claim 1 in which the aroma tic acid component of the copolyester represents -65% of the acid components of the copolyes er. ,l The products of this invention are particularly useful as substrates for flexible coatings fis aggggg g g gg t zr gg ggz figi i such as plasticized cellulose derivatives, including ethyl cellulose, cellulose nitrate, cellulose ace- $2333? and 60 parts of ethylene glycol tereph tate, cellulose acetobutyrate, and cellulose aceto- 4. The product' of clam 1 m which the of properties which adapt the product for the 1 different purposes for which non-woven fabrics g and felts are now used. As examples of some iof these uses may be mentioned'the use of soft felt in wadding, slightly harder felt in coat and 2,} shoe linings, upholstery, millinery, filtering media and insulation.

propionate. The non-woven fabrics herein described are also useful as a base for flexible synthetic resin coatings comprising polyvinyl acetals, polyvinyl halides, polymethacrylic acid esters, amino aldehyde resins and alkyd resins. The present invention is particularly adapted to the production of high strength substrates for plasticized polyvinyl chloride coatings used as upholstery fabrics. The flexible coatings may be applied from solutions or deposited from suspensions in which the film former of the coating is suspended in a non-solvent for said film former, and the film formed by heating after it is applied to the substrate. Where the film former is sustural fiber is nylon and the binder is a copolyester of 40 parts of ethylene glycol sebacate and 60 parts of ethylene glycol terephthalate.

5. The process of preparing non-woven fabrics which comprises matting staple fibers selected from the group consisting of cotton, nylon, viscose rayon, cellulose acetate, polyethylene terephthalate, polymers of acrylonitrile, wool and glass, mixing a dry binder with said matted staple fibers, said binder comprising a linear copolyester of (a) at least one polymethylene glycol ester of an acyclic dicarboxylic acid of the formula HOOC-CMCHa-COOH wherein X is a linear chain composed oi. 4 to 9 atoms, in the chain or which not more than 3 may be oxygen atoms and the remaining are hydrocarbon carbon atoms, any two such oxygen atoms being separated by at least two such carbon atoms, the hydrocarbon carbon atoms being saturated and containing a total ofnot more than three hydrocarbon carbon atoms as side chain substituents, with (b) at least one polymethylene glycol ester of a symmetrical aromatic dibasic acid from the group consisting of terephthalic acid. bibenzoic acid, ethylene bis p-oxy-benzoic acid, tetramethylene bis p-oxy-benzoic acid and 2,6- naphthalic acid, the aromatic acid comprising from 30% to 70% by weight 01' the acid components oi. the copolyester and the polymethylene glycol component of (a) and (b) having from 2 to 6 carbon atoms. and subjecting the mat and binder to heat and pressure sumcient to activate the adhesiveness of the copolyester, the binding material being present in amount between 10% and 65%, based on the combined weight of the binding material and the structural fibers.

6. The process of claim 5 in which the aromatic acid component or the copolyester represents 55-65% of the acid component of the copolyester.

7. The process of claim 5 in which the binder is a copolyester of 40 parts of ethylene glycol sebacate and 60 parts of ethylene glycol terephthalate.

8. The process or claim 5 in which the structural fiber is nylon and the binder is a copolyester of 40 parts of ethylene glycol sebacate and 60 parts of ethylene glycol terephthalate.

9. The process of preparing non-woven fabrics which comprises matting a mixture of structural fibers and dry binding fibers, said structural fibers selected from the group consisting of cotton, nylon, viscose rayon, cellulose acetate, polyethylene terephthalate, polymers of acrylonitrile, wool and glass, said binder fibers comprising a linear copolyester of (a) at least one polymethylene glycol ester of an acyclic dicarboxylic acid 01' the formula HOOO-CHzXCHwCOOH wherein X is a linear chain composed ,of 4 to 9 atoms, in the chain of which not more than 3 may be oxygen atoms and the remaining are hydrocarbon carbon atoms, any two such oxygen atoms being separated by at least two such carbon atoms, the hydrocarbon carbon atoms bein saturated and containing a total oi. not more than three hydrocarbon carbon atoms as side chain substituents, with (b) at least one polymethylene glycol ester of a symmetrical aromatic dibasic acid from the group consisting of terephthalic acid, bibenzoic acid, ethylene bis p-oxy-benzoic acid, tetramethylene bis p-oxy-benzoic acid and 2,6-naphthalic acid, the aromatic acid comprising from 30% to 70% by weight of the acid components of the copolyester and the polymethylene glycol component of (a) and (b) having from 2 to 6 carbon atoms, and subjecting the matted mixture to heat and pressure sufllcient to activate the adhesiveness oi! the copolyester, the binding fibers being present in amount between and 65% based on the combined weight of the binding fibers and the structural fibers.

10. The process 01' claim 9 in which the aromatic acid component of the copolyester represents 55-65% of the acid component of the copolyester. 11. The process of claim 9 in which the binder fiber is a copolyester of 40 parts of ethylene 8 7691 thalate..

12. The process 01 claim 9 in which the structural fiber is nylon and the binder fiber is a copolyester of 40 parts of ethylene glycol sebacate and 60 parts of ethylene glycol terephthalate.

13. A non-woven fabric comprising compacted structural staple fibers selected from the group consisting of cotton, nylon, viscose rayon, cellulose acetate, polyethylene terephthalate, polymers of acrylonitrile, wool and glass bound together by a melt blend of (1) a linear copolyester of (a) at least one polymethylene glycol ester of an acyclic dicarboxylic acid or the formula HOOC-CHzXCHr-COOH wherein X is a linear chain composed of 4 to 9 atoms, in the chain of which not more than 3 may be oxygen atoms and the remaining are hydrocarbon carbon atoms, the hydrocarbon carbon atoms being saturated and containing a total of not more than three hydrocarbon carbon atoms as side chain substituents, with (b) at least one polymethylene glycol ester of a symmetrical aromatic dibasic acid from the group consisting of terephthalic acid, bibenzoic acid, ethylene bis p-oxy-benzoic acid, tetramethylene bis p-oxybenzoic acid and 2,6-naphthalic acid, the aromatic acid comprising from 30% to by weight of the acid components or the copolyester and (2) a linear polyester of at least one linear polymethylene glycol ester 0! a symmetrical aromatic dibasic acid from the group consisting of terephthalic acid, bibenzoic acid, tetramethylene bis p-oxy-benzoic acid, and 2,6-naphthalic acid, the polymethylene glycol component of (1) and (2) having 2 to 6 carbon atoms, the total aromatic acid content of the blend being from 30% to 70% by weight of the acid components of the blend, the binding material being present in amount between 10% and 65%, based on the combined weight of the binding material and the structural fibers.

14. A non-woven fabric comprising staple nylon fibers bound together by a linear copolyester of ethylene glycol sebacate and ethylene glycol terephthalate.

15. The product 01' claim 14 in which the binder comprises 40 parts of the ethylene glycol sebacate and 60 parts of the ethylene glycol terephthalate.

16. The process of preparing non-woven fabrics which comprises matting staple nylon fibers, mixing therewith a dry linear copolyester oi ethylene glycol sebacate and ethylene glycol terephthalate, and subjecting the assembly to heat and pressure sufiicient to render the copolyester adhesive.

17. The process of claim 16 in which the copolyester is introduced as dry particles.

References'Clted in the file of this patent UNITED STATES PATENTS Number Name Date 2,277,049 Reed Mar. 24, 1942 2,357,392 Francis Sept. 5, 1944 2,476,282 Castellan July 19, 1949 2,543,101 Francis Feb. 27, 1951 2,544,019 Heritage Mar. 6, 1951 2,569,169 Heritage Sept. 25, 1951 FOREIGN PATENTS Number Country Date 623,309 Great Britain May 16, 1949 

16. THE PROCESS OF PREPARING NON-WOVEN FABRICS WHICH COMPRISES MATTING STAPLE NYLON FIBERS, MIXING THEREWITH A DRY LINEAR COPOLYESTER OF EHTYLENE GLYCOL SEBACATE AND ETHYLENE GLYCOL TEREPHETHALATE, AND SUBJECTING THE ASSEMBLY TO HEAT AND PRESSURE SUFFICIENT TO RENDER THE COPOLYESTER ADHESIVE. 